Algorithms gross errors

Rectification accounts for systematic measurement error. During rectification, measurements that are systematically in error are identified and discarded. Rectification can be done either cyclically or simultaneously with reconciliation, and either intuitively or algorithmically. Simple methods such as data validation and complicated methods using various statistical tests can be used to identify the presence of large systematic (gross) errors in the measurements. Coupled with successive elimination and addition, the measurements with the errors can be identified and discarded. No method is completely reliable. Plant-performance analysts must recognize that rectification is approximate, at best. Frequently, systematic errors go unnoticed, and some bias is likely in the adjusted measurements. 

Then the values of the test statistic for all combinations are compared with the critical value. The presence of gross errors correspond to the combinations with the low objective function value (ofv). Detailed algorithms for Stages 1 and 2 are included in Appendix B. 

Figure 5-92cshows an RMSEP plot diat displays erratic behavior. This type of plot is obseised when the algorithm is not able to model the concentration variations. It casalso result when gross errors are present in the reference values (e.g., transcaption errors in the concentration values, mixed up samples, and/or poor r ence methods). 

In the last decades many algorithms have been developed for the adjustment of geodetic networks. Apart from the determination of the unknown coordinates of points, indications to the efficiency of an adjustment (check of observations, gross errors) have become very important. With efficient algorithms to solve large equation systems on modern computers, networks with thousands of unknowns can be handled (Griindig 1975 Schek 1976 Strobel 1984). 

In Equation 20-59, viscosity drops out identically, since the same filtrate flows through the mudcake as through the flushed zone in the rock. However, any attempt to use Equation 20-59 would produce gross numerical error and poor physical resolution in the mudcake, since identical grid sizes Ax are implicit in its derivation. Also, the fact that Equation 20-59 is not as numerically stable as Pi-1 2pi + Pi+i = 0, say, would lead to inaccuracies if our algorithm were... 

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